A new report by Massachusetts economists finds New Mexico and the rest of the Southwest will be short a lot of water in the next century if current consumption and growth continue, even if the amount of moisture stays the same.

Add even a minimal amount of climate change, with predicted warmer temperatures and less snow, and the picture looks worse both in terms of water and costs, write economists Frank Ackerman and Elizabeth A. Stanton of U.S. Center of the Stockholm Environment Institute.

Solving the water shortage at the cheapest price will take some hard choices, the authors say.

The two economists analyze the economic cost of the water shortfall in the February report The Last Drop: Climate Change and the Southwest Water Crisis. Their estimate: more than $7 billion a year across the Southwestern states to cover water shortages.

SEI, founded in 1989, is a nonprofit research affiliate of Tufts University that purports to bridge "science and policy." The researchers used dozens of studies from the last decade and three new computer models to analyze water usage, water shortfalls and water costs into 2110 for New Mexico, California, Arizona, Utah and Nevada. All five states rely heavily on groundwater and the Colorado River for the bulk of their water supplies.

All three models show "water demand outstripping water supply in the near future." The research predicts a shortfall of 83 million acre feet of water in New Mexico by the end of the century.

Agriculture continues to use the bulk of the water in all five states. In New Mexico alone, an estimated 78 percent of water consumption goes for hay, crops and livestock, according to 2009 data from the U.S. Geological Survey. Shifting some of that water to high-value crops or other uses is one way to reduce water consumption, say Stanton and Ackerman.

But, they note, "the laws governing water rights in the Southwest are Byzantine in their complexity and allow some low-value uses of water to continue while others would gladly pay much higher prices for the same water, if it were available for purchase," they write.

The researchers put a value on crops that is based on the value of the product compared to the water required to grow them. That varies state by state. In all five, the highest value crops are nursery, greenhouse produce, flowers and sod. Nursery products in New Mexico were valued at $10,463 per acre-foot of water used. Unlike the other four states, dairy and beef cattle were the next highest value at $1,161 per acre-foot, followed by vegetables, melons and sweet potatoes.

On a high note, the report shows New Mexicans using the least amount of water per person among the five states. New Mexico domestic water use is 107 gallons per person per day, compared to 190 gallons per person per day in Nevada and 140 gallons per person in Arizona.

Contact Staci Matlock at 986-3055 or smatlock@sfnewmexican.com.

ON THE WEB

To read the full report: http://sei-international.org/publications.